Barrie Cassidy’s pronouncement on Sunday’s Insiders program that Julia Gillard would not lead Labor to the next election set in train a feverish round of fresh speculation over the Labor leadership — central to the thesis was that Maribyrnong MP Bill Shorten would be the key to a last-minute move away from Gillard. The idea rested on the notion that Shorten had six or seven votes in his pocket in the manner of a senior Japanese LDP official. Left unexplained was where those votes — apparently from current Gillard supporters that take advice from Shorten — were meant to come from.

On Crikey‘s notional numbers, based on media statements, previous voting records, off-the record briefings and factional alignments, the ALP’s 102 member caucus would be split 56-46 in favour of Gillard if a ballot were held today (last February’s leadership ballot was 71-31). So a change of leadership to Rudd would require just six MPs to change their minds.

ALP members in the House are split 39-32 (see our full table here) in favour of Gillard, and Labor members of the Senate 17-14. In the Senate, every sitting NSW Labor Senator would appear to now back Rudd.

These lists are dynamic and we’ll keep them updated online as the numbers move.

However, drill down into the data and any further shifts from the Gillard to the Rudd camp are questionable. For example, the one Gillard-supporting MP who is very close to Shorten, Melbourne Ports’ Michael Danby, would be highly unlikely to take explicit direction. The Shorten-Conroy alliance in Victoria is also not necessarily a hand-in-glove arrangement, as witnessed in the recent Gellibrand preselection, where each powerbroker took a different perspective on the viability of eventual victor Tim Watts (Conroy himself is unlikely to budge on the leadership).

McEwen MP Rob Mitchell is more in the Conroy camp, and Mark Dreyfus is out on a limb. WA Senator Glenn Sterle is close to Shorten and Danby but with his electorate office 3000 kilometres away, isn’t exactly in their immediate sphere.

The NSW Right appears to have shifted to Rudd, but not everyone. For example, when it came to the crunch, which way would the Member for Watson jump?

The other scenario, a change of heart from South Australian right-wing shop assistants’ powerbroker Don Farrell, might have more plausibility — but look again and you’re really talking about Gillard supporters Kate Ellis and Amanda Rishworth, neither of whom would take kindly to an order (even if it came from their former mentor).

Shorten’s influence then is more likely to play out with a Gillard resignation. A change of heart — possibly channelled through an elder statesman such as Bob Hawke — would more likely lead to a Rudd victory in an uncontested ballot, rather than another vote. Shorten’s support then is best viewed as amorphous and representative of a wider sentiment, rather than numerically testable. This would also avoid the problem of sullying Shorten’s public reputation as a hatchet man — it would be about “opening the floodgates” rather than an edict.

One intriguing view doing the rounds is that a post-election Labor rump would be more likely to contain MPs in Shorten’s sphere of influence. A wipeout in Western Sydney, for example, would leave the NSW Right devastated and Shorten’s Victorian base largely preserved, explaining a lack of action. However several Labor sources have dismissed that suggestion as a “conspiracy theory”.